Prism.



any MAOfiL-JL PRISM.

APPLICATION FILED DEO.1, 1913.

Patented May 5, 1914.

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CARL SCH'UTZ, OF CASSEL, GERMANY.

PRISM.

Specification of Letters Patent.

Application filed December 1, 1913.

Patented May 5, 1914. Serial No. 804,033.

To (/71 zr/mm it may concern:

Be it known that I, CARL Scnii'rz, a subject of the German Emperor, andresident of tassel. in the (lei-man Empire, have invented an Improvedand Novel Prism, of which the following is a specification.

Regarding the construction of prisms, which are employed in telescopesand other optical instruments and which have totally refracting surfacesas active surfaces, there has always existed the tendency to diminishthe number of the changes of media, and it is in pursuance of thistendency that two coacting prisms have been united by putty with eachother. This layer of putty has. however, a lightwcakening ell'ect, evenif the best material is employed, and if. moreover, also a diaphragmbecomes necessary, the superposed surfaces form the source for a varietyof objectionable features. First, if no putty has been employed, therespective surfaces become dull after some time of use; second, if puttyhas been employed, the thus effected connection is not durable,especially with regard to instruments connected to firearms. so that theprisms become displaced with regard to each other after some time;finally the mounting of such prisms with regard to each other is verydifiicult. All these drawbacks are entirely overcome by my present.invention, the gist of which resides in making the two prisms integral.Manufacturing such prism body is, however, particularly difficult if oftwo surfaces which join under an angle of less than 180 one or the otheris to be ground and polished. Now, according to the. present invention,such a surface is elongated beyond the line of intersection of the twosurfaces into the other surface by means of incisions of such a kindthat the first mentioned surface may be ground and polished throughoutits whole extent. After this, the incisions are, or may be, filled up.

with a non-transparent material and transformed into a diaphragm.

In order to make my invention more clear, I refer to the accompanyingdrawing, in which similar letters denote similar parts throughout theseveral views, and in which:

Figures 1 and 3 are diagrammatical representations of two differentforms of construction of my improved prism; Fig. 2 shows two coactingporro-prisms.

Referring first to Fig. 2, the ray of light, after having passed throughthe objective,

strikes the surface 1 in the point 2 at a right angle to this surface;itthen passes to the point 25 of the surface at, is totally reflected atand from this point to the point 5 of the surface (3, is again totallyreflected, and leaves the prism at and through the point 7 of thesurface 1 The ray now passes through the air to the other prism makingthcn exactly the same way through this second prism as has just beendescribed with respect to the first of the two prisms. It leaves thesecond prism at the surface S, passing then into the ocular.

The prism system just mentioned can but diflicultly be mounted becausethe fastening must be etfcctcd at the broken edges 9-10 and 11-12. Toobviate the passage of the ray of light through the air, it would benecessary to connect the prisms by putty, and by displacing the same inregard to each other in the direction of the ray of light, passing fromone prism into the other, their relative position being then thatrepresented in Fig. 3, but the invention provides a union not by puttyor the like but by the material of the prisms themselves, 11. e. bymaking the two prisms integral, or in one respectively. The favorableeffect so obtained may be still considerably increased by giving theprism body the shape shown in Fig. 1. The ray enters the prism body atright angles to the surface 13, and after having been totally reflectedfour times within the prism body it leaves the latter through thesurface 1% atright angles to the same. The two prisms forming the prismbody are coherently united with each other at the quadrangle 15, 16, 17,18, there being thus no superposed refracting surfaces or puttysurfaces, which always cause a loss of light. Moreover, the working upof two surfaces is saved, which, is also worth to be mentioned.Supposed, a diaphragm be required at the place in question, it is onlynecessary to make an incision at the shaded portion 01 the prism body bymeans of a saw and to fill up this incision afterward with black varnishor lacquer, black paper or the like. The whole prism body resembles nowa simple lens in so far as only one point of entrance and only one pointof exit exists, and there is, moreover, the further advantage that thelarge surface 15, 19, 20, 21, 17, 22 may be utilized for mounting theprism body, which,

besides, is true also of the similarly shapedand situated surface of thelower side of the prism body. Furthermore the location of that surfaceis suclr that the prism body when mounted in operative position retainsits stable equilibrium. Finally, also the advantage that all surfacesare accessible for cleaning is worth to be mentioned.

The form of construction represented in Fig. 1 allows also of a certainsaving in material because pieces may be cut off parallel to thesurfaces 19, 15, 16, 23 and 15, 22, 24, 16, the thickness of said piecesbeing such that the section lines are tangents to circles inscribed intothe squares 19, 20, 21, 17 and 18, 25, 26, 24.

Having now described my invention, what I desire to secure by LettersPatent of the United States is:

1. A prism body composed of two prisms adapted to co-act and beingintegral one with the other, and an incision 0r incisions situated atand between two prism surfaces joining under an angle of less than 180,substantially as described.

2. A prism body composed of two prisms adapted to co-act and beingintegral one with the other, and an incision or incisions situated atand between two prism surfaces joining under an angle of less than 180,the position of said incision or incisions being such as to elongate, ofthe two surfaces, that to be ground and polished into the other onebeyond the section line of them, substantially as described and for thepurpose as set forth.

A prism body composed of two prisms adapted to eo-act andheing integralone with the other, and an incision orincisionssituated at and betweentwo prism surfaces joining under an angle of less than 180, and anontransparent filling-out material located Within said incision orincisions, substantially as described and for the purposes as set forth.

In testimony whereof I affix my signature in presence of two witnesses.

CARL soHUTz.

\Vitnesses FERDINAND Pii'rz, ERNST Bonn-En.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. C."

